The present invention relates to an ink recording head, to a method of driving the ink recording head, and to an ink injecting method including the ink recording head to provide on record paper an output image capable of dealing with wide needs of from the printing industry where high-speed output of high quality image is requested to the printer industry based on office or personal request, and of the civil article industry requesting low-priced general output devices or the like using a variety of kinds and uses of record paper.
FIG. 10 shows an example of a method of driving an ink recording head used in a conventional electrostatic acceleration type ink jet recording system. FIG. 10 is a perspective view of an ink recording head. In FIG. 10, a plurality of record electrodes 13 are installed in the head, a voltage is applied to an opposed electrode whose illustration is omitted in FIG. 10 and ink is injected by applying high voltage only to a selected electrode such that a potential difference between the selected electrode and the opposed electrode is increased. The electrodes 13 are divided into a number of electrodes between an upper plate 12a and a lower plate 12b to form ink supply ports 11 at predetermined intervals and are arranged as spacers. When ink (not shown) is injected into the ink supply port 11, since the electrode 13 is wetted by the ink, the partitioned supply port 11 is concealed and the ink 2 forms continuous meniscus. Under such a continuous state, when high voltage pulses are applied while selectively scanning a plurality of the record electrodes 13, an ink drop is injected only from a vicinity of a position of the electrode applied with the pulse voltage. (Refer to JP-A-56-167465)
However, in the record head and the recording method in the conventional electrostatic acceleration type ink jet recording system, there have been the following problems.
(1) When intervals among the plurality of record electrodes installed in the head are set to be sufficiently smaller than a distance between the head and the opposed electrode in order to obtain a high resolution, in carrying out printing, since a constant voltage pulse is applied only to the record electrode for injecting the ink, a large potential difference is produced between the selected record electrode and the nonselected record electrode and its influence becomes more significant than in respect of the opposed electrode. Since the record electrode supplies electric charge to the ink and the adjacent record electrodes are electrically connected via the ink, voltage drop is caused between the adjacent electrodes, a potential difference necessary for injecting the ink is not produced and there is a case in which the ink is not injected or the selectivity of the position of injecting the ink is deteriorated.
(2) Density of the ink injected from the head is determined by properties of the ink and in order to express an intermediary tone by changing the density, there has been only such means as for injecting the ink to the same position by a plural number of times, or expressing the intermediary tone by a magnitude of an area, or preparing several kinds of inks.